An electrochromic polymer, a method for preparing the same, and an electrochromic polymer film

Abstract

Provided are an electrochromic polymer, a preparation method thereof, and an electrochromic polymer film, the electrochromic polymer comprising a compound as shown in the following structural formula: wherein R1 is a branched alkyl group with 12 or more carbons, R2 is a straight-chain alkyl group with 6 or more carbons, m1 and m2 represent the number of repetitions of the unit, and n represents the degree of polymerization, with n being a natural number from 8 to 120. The polymer is prepared by direct arylization polymerization.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrochromic technology, in particular to an electrochromic polymer and a preparation method thereof and an electrochromic polymer film. BACKGROUND

[0002] Electrochromic materials can undergo reversible redox reactions under the action of suitable external voltage and exhibit reversible color conversion, which has important application prospects in many fields such as smart windows, non-emitting displays, etc. Among them, electrochromic materials with wide absorption capacity in the visible light range have strong application demand, especially for smart windows, so many research works are committed to realizing the color conversion from black to transparent. In order to realize this function, the main solutions include chemical copolymerization, physical blending, thin film stacking, etc., and it is of great significance to develop a simple copolymerization reaction to prepare a polymer with wide spectral absorption in the field of electrochromic materials.

[0003] Based on the donor-acceptor type polymer with double-band absorption characteristics, the reasonable collocation of donor monomer and double acceptor monomer can effectively realize the wide spectrum absorption. First, the donor monomer with large planar conjugated structure, indacendithiophene (IDTT) or tris(thienothiophene) (TTT), and two acceptor monomers with strong and weak, 5,8-bis(4-(2-butyl octyl)-5-bromothiophene-2-yl)-dithieno[3,2":3,4;2,3":5,6]benzo[1,2-c][1,2,5]thiadiazole (TBT-Br) and 4,7-dibromo-2,1,3-benzothiadiazole (TZ-Br), are selected to obtain a polymer by copolymerization. Two kinds of donor-acceptor structures are formed in the polymer, and the absorption peaks of the two structures are complementary, so that the copolymer obtains the wide spectrum modulation ability. At the same time, in order to make the coloration of the polymer closer to black, the proportion of the two acceptor monomers should be carefully regulated, for example, the increase of TZ proportion may lead to the increase of the absorption of red light (>600 nm) of the polymer, and finally the coloration of the polymer is biased to blue. Therefore, the reaction conditions of direct arylation polymerization are optimized, and the proportion of each monomer is adjusted to obtain a uniform black electrochromic material.

[0004] In recent years, in the field of organic photovoltaics, the structure of thieno[3,2-b]-thiophene (TT) has been widely used, and homopolymers of TT derivatives, such as poly(indacen dithieno[3,2-b]thiophene) (PIDTT) and poly(tris(thienothiophene)) (PTTT), have been proven to have strong and wide absorption spectrum. On the one hand, the unique coplanar "ladder" structure of IDTT units and TTT units effectively increases the degree of delocalization of π electrons, making them highly electron-rich, thus having stronger electron-donating ability and higher HOMO energy level, and the characteristic absorption peak caused by π-π* transition is red-shifted from the ultraviolet light band to the visible light band. On the other hand, 5,8-bis(4-(2-butyloctyl)thiophene-2-yl)-dithieno[3,2":3,4;2,3":5,6]benzo[1,2-c][1,2,5]thiadiazole (TBT) is introduced as a middle-gap acceptor monomer, which is based on 2,1,3-benzothiadiazole (TZ) and fuses two thiophenes, which can effectively reduce the overall electron-withdrawing ability, and the two independent thiophenes connected by a single bond can act as a bridge for π electrons, while TZ is a common acceptor monomer with a relatively narrow band gap, which is commonly used to construct D-A type conjugated polymers. At the same time, in addition to the conjugated structure, the long-chain alkyl groups linked to the side of IDTT, TTT and TBT also give them good solubility to obtain electrochromic polymers that can be used for solution processing. However, there is currently no report on related polymers. SUMMARY

[0005] The purpose of the present application is to provide an electrochromic polymer, a preparation method thereof and an electrochromic film comprising the electrochromic polymer, which contains indacen dithieno[3,2-b]thiophene (IDTT) or tris(thienothiophene) (TTT), 5,8-bis(4-(2-butyloctyl)-2-yl)-dithieno[3,2":3,4;2,3":5,6]benzo[1,2-c][1,2,5]thiadiazole (TBT), and 2,1,3-benzothiadiazole (TZ) units in the structure, has black-to-transparent transition ability, and is prepared by a direct arylization polymerization method. Two new random quaternary conjugated polymers are synthesized.

[0006] The technical solution of the present application is to first provide an electrochromic polymer with black-to-transparent transition ability, which comprises a compound as shown in the following structural formula:

[0007]

[0008] Wherein, R1 is a branched alkyl group with 12 carbons or more, R is a linear alkyl group with 6 carbons or more, m1, m2 represent the number of repeating units, n represents the degree of polymerization, m1 and m2 are natural numbers greater than or equal to 1, and n is a natural number between 8 and 100; preferably, R1 is a single branched alkyl group, the single branched alkyl group is connected to the 2nd or 3rd carbon position of the main chain, and the number of carbon atoms in the single branched alkyl group and the number of carbon atoms in the main chain differ by less than or equal to 4; specifically, the main chain is represented by the following formula: The electrochromic polymer has a color change characteristic of black to transparent transition.

[0009] The compound shown in the structural formula includes indacene dithieno[3,2-b]thiophene (IDTT) or tris(thienothiophene) (TTT), 5,8-bis(4-(2-butyloctyl)-2-yl)-dithieno[3,2":3,4;2,3":5,6]benzo[1,2-c][1,2,5]thiadiazole (TBT), and 2,1,3-benzothiadiazole (TZ) units.

[0010] The application also provides a preparation method of the electrochromic polymer, comprising the following steps:

[0011] 1) preparing the polymer by direct arylation polymerization: adding indacene dithieno[3,2-b]thiophene or tris(thienothiophene) (M1), 5,8-bis(4-(2-butyloctyl)-5-bromothiophene-2-yl)-dithieno[3,2":3,4;2,3":5,6]benzo[1,2-c][1,2,5]thiadiazole (M2), 4,7-dibromo-2,1,3-benzothiadiazole (M3), potassium carbonate, dimethylacetamide, pivalic acid and palladium acetate into a two-neck flask connected with an atmosphere protection and condenser tube, replacing the gas, maintaining the atmosphere protection behavior in the flask, heating the mixture to react, cooling to room temperature, dropping the reaction solution into methanol for precipitation, and collecting the black precipitate by filtration;

[0012] 2) purifying the polymer by Soxhlet extraction: wrapping the black precipitate with filter paper, placing it in a fat extractor, washing it with methanol, n-hexane and chloroform in sequence, concentrating the chloroform washing liquid, dropping it into methanol for precipitation, and collecting the precipitate by filtration, which is the purified electrochromic polymer.

[0013] The synthesis route is as follows:

[0014]

[0015] or

[0016]

[0017] wherein R1 is a linear alkyl group with 12 carbons or more, R2 is a branched alkyl group with 8 carbons or more, m1, m2, and n each represent a polymerization degree, m1 and m2 are natural numbers greater than or equal to 1, and n is a natural number between 8 and 100, preferably, R1 is a single branched alkyl group, the single branched alkyl group is connected to the 2nd or 3rd carbon position of the main chain, and the number of carbon atoms in the single branched alkyl group and the number of carbon atoms in the main chain differ by less than or equal to 4, and specifically,

[0018]

[0019] Further, in the step 1), the molar ratio of indaceno[3,2-b]thiophene or tris(thienothiophene) (M1) to 5,8-bis(4-(2-butyloctyl)-5-bromothiophen-2-yl)-dithieno[3,2':3,4;2',3":5,6]benzo[1,2-c][1,2,5]thiadiazole (M2) is (3:1)-(2:1), and the molar ratio of indaceno[3,2-b]thiophene or tris(thienothiophene) (M1) to 4,7-dibromo-2,1,3-benzothiadiazole (M3) is (2:1)-(3:2).

[0020] Further, in the step 1), the molar ratio of indaceno[3,2-b]thiophene or tris(thienothiophene) (M1) to potassium carbonate is 1:4, the molar ratio of indaceno[3,2-b]thiophene or tris(thienothiophene) (M1) to palladium acetate is 1:(0.01-0.02), the molar ratio of indaceno[3,2-b]thiophene or tris(thienothiophene) (M1) to pivalic acid is 1:1, and the amount of dimethylacetamide used is such that the total concentration of the reaction monomers is 0.1 mol / L.

[0021] Further, in the step 1), the reaction temperature is 100-120°C, and the reaction time is 48-96 h.

[0022] Further, in the step 2), the purification process is a Soxhlet extraction process, and methanol, n-hexane, and chloroform are used in sequence for extraction, and the chloroform solution is precipitated.

[0023] The application also provides an electrochromic polymer film, which is obtained by spraying or blade coating the electrochromic polymer with black to transparent transition capability provided by the application, and the film thickness of the polymer film is 200-800 nm. The electrochromic polymer with black to transparent transition capability can be formed into a film on the surface of a conductive substrate by solution blade coating and spraying, and the color of the film can be converted between black and transparent states, and the film has the characteristics of low driving voltage, high optical contrast, and high stability, and is suitable for the assembly of electrochromic devices.

[0024] The advancement of the present application compared to the prior art is that:

[0025] 1) The electrochromic polymer provided by the present application contains inda dithieno [3, 2-b] thiophene (IDTT) or tris (thienothiophene) (TTT), 5, 8-bis (4- (2-butyl octyl) -2-yl) -dithieno [3, 2': 3, 4; 2, 3": 5, 6] benzene [1, 2-c] [1, 2, 5] thiadiazole (TBT), 2, 1, 3-benzothiadiazole (TZ) units in the multi-copolymer, so that the electrochromic polymer with black to transparent transition ability and the electrochromic polymer film containing it exhibit a wide spectral absorption behavior, can display black to transparent color change, and have high contrast, fast response rate and high stability, and can be applied in electrochromic devices.

[0026] 2) The polymer prepared by the present application has alkyl side chains. On the one hand, the alkyl side chain substitution is commonly used to increase the solubility of the polymer in organic solvents (such as chloroform), which can make the polymer have solution processing ability, and due to the low solubility of the polymer rigid main chain, a sufficient length of alkyl side chain is needed to produce the effect. On the other hand, the long alkyl side chain adopts a branched structure to reduce steric hindrance and improve the main chain regularity.

[0027] 3) The present application uses a direct arylization polymerization method to prepare two new types of random ternary conjugated polymers, the preparation process is simple, and compared with other chemical polymerization methods (such as Stille coupling and Suzuki coupling), no organotin reagent is used, the reaction process is more green and environmentally friendly, and can be used for large-scale synthesis of electrochromic polymers.

[0028] 4) The monomer ratio involved in the present application is systematically analyzed, and the absorption spectrum and color development of the final polymer can be changed by simply adjusting the monomer ratio. BRIEF DESCRIPTION OF DRAWINGS

[0029] These and / or other aspects and advantages of the present application will become more apparent and more readily appreciated from the following detailed description of the embodiments of the present application, taken in conjunction with the accompanying drawings in which:

[0030] Figure 1 The nuclear magnetic hydrogen spectrum of the target polymer IDTT-TBT-TZ-3-1-2 obtained in the embodiment of the present application;

[0031] Figure 2 The nuclear magnetic hydrogen spectrum of the target polymer TTT-TBT-TZ-2-1-1 obtained in the embodiment of the present application;

[0032] Figure 3Spectra absorption curves and color photos of the polymers obtained in the examples of the present application dissolved in chloroform, wherein (a) is the spectra absorption curve of the target polymer IDTT-TBT-TZ-3-1-2; (b) is the color transformation photo of the target polymer IDTT-TBT-TZ-3-1-2; (c) is the spectra absorption curve of the target polymer TTT-TBT-TZ-2-1-1; (d) is the color transformation photo of the target polymer TTT-TBT-TZ-2-1-1;

[0033] Figure 4 UV-Vis absorption spectra and color transformation photos of the copolymer films obtained in the examples of the present application at different potentials, wherein (a) is the UV-Vis absorption spectrum of the target polymer IDTT-TBT-TZ-3-1-2; (b) is the color transformation photo of the target polymer IDTT-TBT-TZ-3-1-2; (c) is the UV-Vis absorption spectrum of the target polymer TTT-TBT-TZ-2-1-1; (d) is the color transformation photo of the target polymer TTT-TBT-TZ-2-1-1;

[0034] Figure 5 Electrochemical cyclic voltammograms of the two copolymer films obtained in the examples of the present application;

[0035] Figure 6 Chrono-transmittance response of the two copolymer films obtained in the examples of the present application;

[0036] Figure 7 Stability curves of the two copolymer films obtained in the examples of the present application;

[0037] Figure 8 Thermal stability curves of the two copolymer films obtained in the examples of the present application. DETAILED DESCRIPTION

[0038] In order for those skilled in the art to better understand the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0039] Example 1

[0040] Preparation of electrochromic polymer 1, 1 mmol of donor monomer indaceno[3,2-b]thiophene (IDTT) and 0.33 mmol of 5,8-bis(4-(2-butyl octyl)-5-bromothiophen-2-yl)- diindathieno[3,2':3,4;2',3":5,6]benzo[1,2-c][1,2,5]thiadiazole (TBT-Br), 0.67 mmol of 4,7-dibromo-2,1,3-benzothiadiazole (TZ-Br) were added into a 50 mL two-necked flask. Then, potassium carbonate (4 mmol), pivalic acid (1 mmol) and palladium acetate (0.01 mmol) were added into the flask, and the mixture was degassed by three freeze / pump / thaw cycles to fill with argon. Then, 20 mL of dimethylacetamide (DMAc) was injected into the flask, and the mixture was degassed and filled with argon again. The mixture was heated to react at 110 °C, and the reaction time was 72 h. After the reaction was completed, it was cooled to room temperature, and the reaction solution was dropped into cold methanol and cooled in a refrigerator for 30 min, and the black precipitate was collected by filtration. The Soxhlet extraction method was used to wash with methanol, n-hexane, and finally chloroform. The chloroform fraction was collected, concentrated by a rotary evaporator, and re-precipitated in cold methanol. Finally, the target polymer was collected by filtration and dried in vacuum. (The target polymer indicates 3-1-2 in the formula, which means the molar ratio of IDTT:TBT:TZ in the raw material is 3:1:2), and the yield was 71%. 1 H NMR (400 MHz, CDCl3) δ: 7.98 (d, 2H), 7.50 (m, 6H), 7.27-7.04 (m, 56H), 2.72 (d, 2H), 2.58 (t, 26H), 1.75 (t, 2H), 1.61 (t, 24H), 1.41-1.15 (m, 104H), 0.88 (t, 36H).

[0041] Preparation of electrochromic polymer 2, 1 mmol of donor monomer tris(thienothiophene) (TTT) and 0.5 mmol of 5,8-bis(4-(2-butyloctyl)-5-bromothiophen-2-yl)-dithieno[3,2':3,4;2',3":5,6]benzo[1,2-c][1,2,5]thiadiazole (TBT-Br), 0.5 mmol of 4,7-dibromo-2,1,3-benzothiadiazole (TZ-Br) were added into a 50 mL two-necked flask. Then potassium carbonate (4 mmol), pivalic acid (1 mmol) and palladium acetate (0.01 mmol) were added into the flask, the mixture was degassed by three freeze / pump / thaw cycles to fill with argon. Then 20 mL of dimethylacetamide (DMAc) was injected into the flask, the mixture was degassed and filled with argon again. The mixture was heated to react at 110 °C, the reaction time was 72 h. After the reaction was completed, it was cooled to room temperature, the reaction solution was dropped into cold methanol, and cooled in the refrigerator for 30 min, the black precipitate was collected by filtration. Soxhlet extraction was used to wash with methanol, n-hexane in turn, and finally with chloroform. The chloroform fraction was collected, concentrated by a rotary evaporator, and re-precipitated in cold methanol. Finally, the target polymer was collected by filtration and dried in vacuum. (The target polymer represented 2-1-1 in the formula, which means the molar ratio of TTT:TBT:TZ in the raw material was 2:1:1), the yield was 66%. 1 H NMR (400 MHz, CDC13) δ: 8.02 (d, 2H), 7.50 (m, 2H), 7.27-7.04 (m, 38H), 2.72 (d, 2H), 2.58 (t, 18H), 1.75 (t, 2H), 1.61 (t, 16H), 1.41-1.15 (m, 80H), 0.88 (t, 36H).

[0042] The proton nuclear magnetic resonance spectra of all copolymers are shown in Figure 1 and Figure 2 .

[0043] Example 2

[0044] The polymer prepared in Example 1 was subjected to solution spectroscopy and electrochemical performance test. The polymer was dissolved in chloroform to prepare a solution with a concentration of 2 x 10 -4 mg / mL, the solution absorption curve and solution picture are shown in Figure 3As shown, the solution color of IDTT-TBT-TZ-3-1-2 is black, and the solution color of TTT-TBT-TZ-2-1-1 is dark green. Through the test of the ultraviolet-visible spectrophotometer, the solution of the two polymers has a relatively wide absorption band, and presents several high absorption peaks, which is the result of the joint action of the π electron transition and the intramolecular charge transfer existing in the copolymer with the double D-A type structure. Among them, the corresponding absorption peaks of the polymer IDTT-TBT-TZ-3-1-2 are at 434 nm and 620 nm, respectively. The corresponding absorption peaks of the polymer TTT-TBT-TZ-2-1-1 are at 467 nm and 651 nm, respectively.

[0045] Preparation of polymer thin film: the polymer is dissolved in chloroform to prepare a solution of 5 mg / ml, the insoluble substances are filtered out through a filter, and then placed in a spray gun, the air pressure is controlled to be 2 MPa, and the spray is carried out on the conductive glass, the thin film absorbance is about 1.0, and after the spray, it is placed in a vacuum drying box for vacuum drying at 40 degrees for standby. A three-electrode system is adopted, in which the polymer film is used as the working electrode, the platinum wire is used as the counter electrode, and the calibrated silver wire is used as the reference electrode, and the supporting electrolyte is a 0.1 mol / L lithium perchlorate propylene carbonate solution.

[0046] Spectroelectrochemical performance test of copolymer film under different voltages. A three-electrode system is adopted, in which the ITO glass sheet (1 cm x 5 cm) loaded with the electrochromic polymer film is used as the working electrode, the silver wire is used as the quasi-reference electrode (calibrated according to Fc / Fc + ) and the platinum wire is used as the counter electrode, and the electrolyte solution is a 0.1 M lithium perchlorate / carbonic acid propylene (LiClO4 / PC) solution. The spectroelectrochemical spectra and colorless coloring photos of the two copolymer thin films under different applied voltages are shown in Figure 4 , it can be easily seen that the electrochromic transition from black to transparent occurs in both electrochromic thin films. And due to the π-π* bond stacking, the spectrum of the polymer thin film has a certain red shift relative to the solution. With the continuous increase of the voltage, the polymer thin film can realize the transition from the high absorption state covering 400-700 nm to the transparent state.

[0047] The electrochemical performance of the copolymer is tested by cyclic voltammetry (see Figure 5 ), and both polymers have a relatively low oxidation potential. Among them, IDTT-TBT-TZ-3-1-2 shows reversible oxidation-reduction coupling at 0.92 V / 0.79 V, and TTT-TBT-TZ-2-1-1 shows reversible oxidation-reduction coupling at 0.74 V / 0.61 V, both of which have obvious reversible oxidation-reduction activity, accompanied by reversible color change.

[0048] The response time refers to the time required for the material to achieve 95% of its maximum transmittance difference. The response time and cycle stability of the polymer were tested by using an ultraviolet-visible spectrophotometer and an electrochemical workstation (see Figure 6 and Figure 7 ), the three-electrode system was connected to the electrochemical workstation, and the quartz cuvette was placed in the ultraviolet-visible spectrophotometer, and the change in transmittance of the polymer film at the maximum transmittance wavelength was measured synchronously while a voltage was applied to the polymer film. The double-potential steps set in the square wave cycle of IDTT-TBT-TZ-3-1-2 at 434 nm were: 0.9 V and 0 V, with a duration of 40 s and 10 s, respectively. The initial optical contrast of IDTT-TBT-TZ-3-1-2 was 42.1%, and after 240 cycles of square wave cycle, the optical contrast decreased to 39.8%; the double-potential steps set in the square wave cycle of TTT-TBT-TZ-2-1-1 at 467 nm were: 1.0 V and 0 V, with a duration of 100 s and 70 s, respectively. The initial optical contrast of TTT-TBT-TZ-2-1-1 was 38.8%, and after 350 cycles of square wave cycle, the optical contrast decreased to 35.5%; and during the switching process, the coloring time (t c ) and bleaching time (t b ) of IDTT-TBT-TZ-3-1-2 were 2.0 s and 17.6 s, respectively; the coloring time (t c ) and bleaching time (t b ) of TTT-TBT-TZ-2-1-1 were 10.3 s and 47.8 s, respectively.

[0049] The thermal stability of the electrochromic polymer was tested (see Figure 8 ): the thermal decomposition temperature of the polymer was greater than 300℃, indicating that it can be applied to a working environment with a higher temperature.

[0050] As can be seen from the above examples, the color and absorption spectrum of the copolymer film prepared by the present application can be controlled by the type of comonomer, the copolymer film can realize the transformation from black to transparent, and has the characteristics of easy processing, high optical contrast, high coloring efficiency and good stability, and the prepared copolymer film can be applied in the fields of smart windows, electrochromic display and self-adaptive camouflage.

[0051] The above has described the embodiments of the present application, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An electrochromic polymer, characterized in that, Including compounds with the following structural formulas: ； Wherein, R1 is a branched alkyl group with 12 or more carbons, R2 is a straight-chain alkyl group with 6 or more carbons, m1 and m2 represent the number of repeating units, n represents the degree of polymerization, m1 and m2 are natural numbers greater than or equal to 1, and n is a natural number between 8 and 100.

2. The electrochromic polymer as described in claim 1, characterized in that, R1 is a single-branched alkyl group, wherein the single branch is attached to carbon position 2 or 3 of the main chain, and the number of carbon atoms on the single branch differs from the number of carbon atoms on the main chain by less than or equal to 4.

3. The electrochromic polymer as described in claim 1, characterized in that, The ; The electrochromic polymer has a color-changing property that transitions from black to transparent.

4. The method for preparing the electrochromic polymer according to any one of claims 1-3, characterized in that, Includes the following steps: 1) Preparation of polymers via direct arylation polymerization: Indadadithiopheno[3,2-b]thiophene or tris(thiophenothiophene) (M1), 5,8-bis(4-(2-butyloctyl)-5-bromothiophene-2-yl)-dithiopheno[3,2":3,4; 2,3":5,6]benzo[1,2-c][1,2,5]thiadiazole (M2), 4,7-dibromo-2,1,3-benzothiadiazole (M3), potassium carbonate, dimethylacetamide, terpentine, and palladium acetate were added to a two-necked flask with an atmosphere protection and condenser at the top. The atmosphere protection behavior in the flask was maintained by evacuation and the mixture was heated to react. After the reaction was completed, it was cooled to room temperature, and the reaction solution was dropped into methanol to precipitate. The black precipitate was collected by filtration. 2) Polymer purification by Soxhlet extraction: The black precipitate was wrapped in filter paper and placed in a fat extractor. It was washed sequentially with methanol, n-hexane and chloroform. The chloroform washing solution was concentrated and added dropwise to methanol for precipitation. The precipitate was collected by filtration, which is the purified electrochromic polymer.

5. The method for preparing the electrochromic polymer as described in claim 4, characterized in that, In step 1, the molar ratio of indadadithienro[3,2-b]thiophene or tri(thienrothiene) (M1) to 5,8-bis(4-(2-butyloctyl)-5-bromothien-2-yl)-dithienro[3,2":3,4; 2,3":5,6]benzo[1,2-c][1,2,5]thiadiazole (M2) is (3:1)-(2:1), and the molar ratio of indadadithienro[3,2-b]thiophene or tri(thienrothiene) (M1) to 4,7-dibromo-2,1,3-benzothiadiazole (M3) is (2:1)-(3:2).

6. The method for preparing the electrochromic polymer as described in claim 4, characterized in that, In step 1: the molar ratio of indadadithio[3,2-b]thiophene or tris(thienothiophene) (M1) to potassium carbonate is 1:4; the molar ratio of indadadithio[3,2-b]thiophene or tris(thienothiophene) (M1) to palladium acetate is 1:(0.01~0.02); the molar ratio of indadadithio[3,2-b]thiophene or tris(thienothiophene) (M1) to tervastatin is 1:1; and the amount of dimethylacetamide used is such that the total concentration of the reactants is 0.1 mol / L.

7. The method for preparing the electrochromic polymer as described in claim 4, characterized in that, The reaction temperature in step 1 is 100~120℃, and the reaction time is 48~96 hours.

8. The method for preparing the electrochromic polymer as described in claim 4, characterized in that, The purification process in step 2 is a Soxhlet extraction process, in which methanol, n-hexane, and chloroform are extracted sequentially, and the chloroform solution is precipitated.

9. An electrochromic polymer film, characterized in that, The polymer film is obtained by spraying or scraping the electrochromic polymer as described in any one of claims 1-3, and the thickness of the polymer film is 200~800nm.

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